1. Field of the Invention
This invention relates to a chlorine dioxide distributor, and more particularly, to a distributor used to mix chlorine dioxide into solution in a bleach tower used as part of a wood pulp bleaching system in a paper making process.
2. Description of the Prior Art
Chlorine dioxide is used in conventional oxidation systems as part of a wood pulp bleaching system in a paper making process.
In one example of such a process, unbleached pulp from a digester is supplied to brown stock washers where it is washed. The washed, unbleached pulp from the washers is conducted to a first stage bleach tower and then passed in sequence through a washer, a first stage caustic extraction tower, a washer, a second stage bleach tower, a washer, a second stage caustic extraction tower, a washer, a third stage bleach tower, and a final washer, supplying bleached, color-lightened, pulp to a paper forming machine.
In the bleach tower, chlorine dioxide or chloride dioxide and chlorine is supplied through a line into an oxidation vessel or tower and color reduction of the pulp stock allowed to take place. Chlorine dioxide or chlorine dioxide in admixture with chlorine, usually in a gaseous state, and pulp stock are pumped into the bleaching tower through a static distributor wherein the bleaching of the cellulosic pulp takes place. One typical static distributor contains a central opening in a dome-shaped surface wherein the pumped chlorine dioxide and pulp stock are allowed to cascade over the sides. The dome is provided with side openings so that radial flowing chlorine dioxide and pulp stock can mix with the cascading chlorine dioxide and pulp stock to ensure more thorough mixing. Another typical static distributor is umbrella shaped but is not provided with a central opening. The mixing takes place but in this instance with the pumped chlorine dioxide and pulp stock impinging on the inner aspect of the umbrella surface and from there cascading downwardly to mix with the radially flowing chlorine dioxide and pulp stack.
The present invention relates to a static distributor providing a more improved flow and mixing than had been previously achieved and which realizes as well a marked energy efficiency.